I've gone a little OCD the past two months on chargers, since I had to replace my old motomaster charger that finally died. I dove into manuals, forums, and ultimately purchased several to observe their behaviors for myself.
Battery Chargers observed:
Noco Genius 3500
CTEK MUS 4.3
Erayak c9002
Schumacher SC3
Schumacher SC1
Battery Tender Junior
Out of all these chargers I've only returned one, the Noco. If you buy one I would highly recommend attaching a voltage meter to it for the first dozen cycles and watching carefully. I was surprised how inconsistent it was. The caution was raised when it was solid green on a wet cell, indicating the charging cycle was completed, and it was still pumping 14.88 volts. I left it for an hour hoping it would drop back to the previously observed 13.8 volts, it did not. The manual states when the solid green light is on the charger goes into maintenance mode, which should only monitor and charge when voltage drops below a certain threshold. My observations are that, in previous cycles in maintenance mode it was keeping a consistent 13.8 volts, indicating it was behaving similar to the CTEKs which hold a consistent 13.6 in stage 7 for up to 10 days before going into maintenance mode. The 'repair' mode also pushes a steady current of 15.8 volts for hours at a time. I could hear the boiling on the wet cells. Regardless of the 14.88v event, and the repair mode current, the observed behavior does not match the algorithm phases and status LEDs as explained in the manual.
That being said, the noco is a nice looking charger, with the parts/connectors and charger itself appearing to be very high quality. Maybe I got a bad one, or maybe the Noco was so wicked smart that it out smarted me and there is some explanation that reconciles the behavior of this charger.
I have spent hours watching and tracking the voltage patterns mapped against the documented algorithms for each charger. The most consistent, after dozens of charge cycles on multiple battery types, is the CTEK. The CTEK behaves exactly as the algorithm is explained in the manual. No deviation, ever.
The best value? The Schumacher chargers. $10 for a battery maintainer (SC1) and $20 for an 8 amp smart charger that both behave exactly as expected and get the job down well and safely. Both smart chargers, with simple 3/4 phase algorithms. The downside is they have fixed cables. So there is no option for interchangeable connectors. If you need ring terminals you will either need to splice in an SAE connector, or use another charger.
Of mention: the Battery Tender Junior algorithm was not what I was expecting. I was expecting it to behave just like the Schumacher SC1, which turns off all current immediately once it reaches 14.2 volts and only provides current again when voltage drops to 12.7 volts. You can clearly see the quick voltage drop from 14.2 when the SC1 turns off. The Tender Junior pumps a relatively steady current with the voltage bouncing between 14.2 and 14.6 initially and narrowing down to 14.5-14.6 volts for several minutes before it goes into maintenance mode. The voltage drop off was also noticeably slower indicating that it is potentially providing a small current to avoid back drain.
Anyway, it has been a fun learning experience for the reasonable price of approximately $200 (once the Noco was returned). I also now have a fleet of chargers, some of which I'll be lending to family/friends (hint: it won't be the CTEK), and hopefully this post will be helpful to others.
Happy Charging
Battery Chargers observed:
Noco Genius 3500
CTEK MUS 4.3
Erayak c9002
Schumacher SC3
Schumacher SC1
Battery Tender Junior
Out of all these chargers I've only returned one, the Noco. If you buy one I would highly recommend attaching a voltage meter to it for the first dozen cycles and watching carefully. I was surprised how inconsistent it was. The caution was raised when it was solid green on a wet cell, indicating the charging cycle was completed, and it was still pumping 14.88 volts. I left it for an hour hoping it would drop back to the previously observed 13.8 volts, it did not. The manual states when the solid green light is on the charger goes into maintenance mode, which should only monitor and charge when voltage drops below a certain threshold. My observations are that, in previous cycles in maintenance mode it was keeping a consistent 13.8 volts, indicating it was behaving similar to the CTEKs which hold a consistent 13.6 in stage 7 for up to 10 days before going into maintenance mode. The 'repair' mode also pushes a steady current of 15.8 volts for hours at a time. I could hear the boiling on the wet cells. Regardless of the 14.88v event, and the repair mode current, the observed behavior does not match the algorithm phases and status LEDs as explained in the manual.
That being said, the noco is a nice looking charger, with the parts/connectors and charger itself appearing to be very high quality. Maybe I got a bad one, or maybe the Noco was so wicked smart that it out smarted me and there is some explanation that reconciles the behavior of this charger.
I have spent hours watching and tracking the voltage patterns mapped against the documented algorithms for each charger. The most consistent, after dozens of charge cycles on multiple battery types, is the CTEK. The CTEK behaves exactly as the algorithm is explained in the manual. No deviation, ever.
The best value? The Schumacher chargers. $10 for a battery maintainer (SC1) and $20 for an 8 amp smart charger that both behave exactly as expected and get the job down well and safely. Both smart chargers, with simple 3/4 phase algorithms. The downside is they have fixed cables. So there is no option for interchangeable connectors. If you need ring terminals you will either need to splice in an SAE connector, or use another charger.
Of mention: the Battery Tender Junior algorithm was not what I was expecting. I was expecting it to behave just like the Schumacher SC1, which turns off all current immediately once it reaches 14.2 volts and only provides current again when voltage drops to 12.7 volts. You can clearly see the quick voltage drop from 14.2 when the SC1 turns off. The Tender Junior pumps a relatively steady current with the voltage bouncing between 14.2 and 14.6 initially and narrowing down to 14.5-14.6 volts for several minutes before it goes into maintenance mode. The voltage drop off was also noticeably slower indicating that it is potentially providing a small current to avoid back drain.
Anyway, it has been a fun learning experience for the reasonable price of approximately $200 (once the Noco was returned). I also now have a fleet of chargers, some of which I'll be lending to family/friends (hint: it won't be the CTEK), and hopefully this post will be helpful to others.
Happy Charging